Fuse-indicator



W. H. HOLDORF.

FUSE INDICATOR.

APPLICATION FILED Aue.2, I9Ia.

1,337,357; Patented Apr. 20, 1920.

Snom/Lto@ MM www J6 W attozuu UNITED sTATEs PATENT oEEicE.

WILLIAM I-I. HOLDORF, 0F MINNEAPOLIS, MINNESOTA.

FUSE-INDICATOR.

Application iled August 2, 1918.

To all whom t may concern:

Be it known that I, WILLIAM H. HoLDonF, a citizen of the United States, residing at Minneapolis, in the county of Hennepin and State of Minnesota, have invented new and useful Improvements inl Fuse-Indicators, of which the following is a specification. This invention relates to a fuse indicator particularly adapted for use inconnection with what are known as reiillable cartridge fuses though capable-of application to and practical operation with any form of fuse embodying a replaceable fuse link, or for permitting withdrawal of a blown fuse link and the substitution of a new link therefor. One object of the invention is to. provide an automatically operating attachment comprising a movable element which may be readily seen from the exterior of the cai'- tridge or analogous device and indicate by its position the condition of a fuse link toenable an observer to determine whether a fuse is practically intactlor has become blown. A further object of the invention is to provide a fuse indicator that may be easily applied to a cartridge fuse or other fuse link holding means by a very simple change in construction or without material modification of the fuse link holding means now commonly used. f

l/Vith these and other objects and advantages in view, the invention consists in the construction and arrangement of the several parts which will be more fully hereinafter.

described and claimed.

For the purposes of practical demonstration of the ready application and efficiency in operation of the improved indicator, one form of cartridge fuse has beenl illustrated in the drawings, but it will be understood that the indicator is not limited in its appli- `cation to this precise construction ofthe vcartridge fuse but .may be applied to any Specification of Letters Patent.

Patented Apr. 20, 1920.

Serial No. 248,011.

and the essential movable element thereof in engagement with the fuse link.

Fig. 2 represents a view similar to Fig. l taken through the cartridge fuse at a different angle and illustrating the movable element or plunger of the indicator in horizontal section.

Fig. 3 represents a transverse vertical section of the cartridge fuse with the improved indicator in set position relatively to the fuse link.

Fig. 4: represents a section similar to Fig. l of a portion of the cartridge fuse showing a blown link and the consequent change of Vposition of the movable parts of the improved indicator.

Fig. 5 represents a detail section of a portion of the cartridge fuse and link of a form different from that shown by Figs. 1, 2, 3 and l and illustrating a slight modification in the structure of the improved indicator.

Fig. 6 is a detail elevation particularly showing the form of fuse link illustrated by Fig. 5 and the position of the indicator relatively thereto.

Fig. 7 represents a detail section of a portion of the cartridge fuse and link of further different form and illustrating a further modification of the movable element or plunger of the improved indicator to accommodate the change in structure of the link.

Fig. 8 is a detail elevation of a portion of the'link shown by Fig. 7 and illustrating the position of the improved indicator relatively thereto.

Fig. 9 is a detail view of the essential movable element orplunger of the indicator and a portion of the casing thereof illustrating a still further modification lof the. plunger.

The form of the cartridge fuse illustrated in the drawings embodies a cylindrical shell i 5 having ferrules or heads 6 secured to opposite ends and each provided with an annular iange 7 bearing against the adyacent end of the shell 5 and also with an internally screw-threaded annular seat 8 to and applied to the seat and when applied is held in fixedfposition by the disk closure 10. The fuse link 12 as shown by Figs. 1, 2, y3 and 4 has its ends removably secured to the disk 9 and bent over against the outer side of the 'disk to dispose the extremities thereof for 'engagement by the adjacent disk closure 10 having an opening 11 to facilitate application and removal thereof, each disk closure 10 being similarly constructed and operating in a similar manner relatively to the adjacent endof the fuse link. This fuse link 12 is reduced, as at 13, on o posite sides of the center, such form of fuse link being well known and need not be further referred to in detail. The improved indicator as shown by Figs. 1, 2, 3 and 4 embodies a casing 14 with an inner closing end 15 and an outer hollow head 16 of larger diameter than the screw-threaded portion of the casing, the casing being fitted in Aa screw-tlireaded opening 17 in the shell 5. Centrally movablel throughA the casingis a plunger 18 carrying a plunger disk 19 movable in the smaller screw-threaded portion of the casing, and between the plunger disk 19 and the outer closed end 20 of the enlarged or hollow head portion 16 of the casing a` spring 21 is interposed and operates to move the plunger 18 inwardly, the plunger being free to move through an opening 22 in the outer closed end 20 'of the hollow head 16 and also through a screw-tlireaded opening 23 in the center of the inner closed end 15 of the reduced portion of the casing 14.

' The plunger 18 has an indicator disk 24 on the outer end thereof and the linner end of this plunger as Shown by all of the figures, except Fig.' 9, is screw-threaded,

as at 25, to engage the threads of the opening 23 and whereby the plunger may be locked against inward movement by rotating the same through the medium of the indicator disk 24 when it is desired to replace a blown fuse disk. As shown by Fig.

9, the inner end of the plunger 18 is smooth or the screw-threads as illustrated by the remaining figures being omitted and indicating that the said plunger will practically operate or perform its intended function yirrespective of the threaded structure at the inner end thereof, said threaded structure being simply an incidental featui'ebf convenience in holding the plunger in operative position Whenrefilling the cartridge with a new fuse, or replacing a blown fuse as hereinbefore indicated. The plunger disk 1.9 insures a positive operation of the plunger, said disk being fixed to the plunger, and this disk also provides a bearing for the inner end of the spring 21 and whereby the-plunger is operated when released from i a set position.

terminal being of a dimension proportion-Y ate to the diameter of the opening 27. rlhe remaining features of the modified indicator as shown by Figs. 5 and 6 are the saine as in the form thereof illustrated by Figs. 1, 2, 3 and 4. Figs. 7 and 8 also show a further forin of fuse link 29 which is materially reduced at the center, as at 30, and in this instance the inner end of the plunger 18 is formed with a yoke 3l to embrace the center of the link 30, the remaining features of the indicator structure als shown by Figs. 7 and 8 being similar to the parts hereinbefore described.

After a fuse link of the usual form shown has been applied or positioned upon the shell 5, the plunger 18 is reduced so that the inner end thereof in either of the forms Shown will bear against or engage the link, and this engagement of the inner end of the plunger with the link will force the indicator disk 24 outwardly fiom the hollow head 16 andv compress the spring 21 between the plunger disk 19 and the outer closed end 20 of the said hollow head. As long as the fuse link is intact, the plunger 18 and its indicator disk 24 will remain in the position particularly shown by Figs. land 3, but when the link is blown, the plungerl 18 is released and the spiing 21 will act to force the plunger inwardly and bring the indicator disk inclose contact with the outer closed end 20 of the hollow head 16, as shown by Fig. 4, and by this means an inspector or observer will be enabled to readily determine that the fuse link has blown and another link may be easily replaced in the cartridge and the in-l dicator reset as shown by Figs. 1 and 3, the plunger 18 being held out during re-v filling of the cartridge with a new link by engagement'of the inner screw-threaded end 25 with the threaded opening 23, or be held out manually when the form of the cartridge shown by Fig. 9 is used.

The improved indicator may be easily and cheaply constructed in view of the simplicity of the parts thereof and will be materially advantageous as a means for quickly notifying an inspector or observer of the condition of a fuse link and whereby a blown fuse link may be readily located and saving of time in refilling cartridges or in replacing blown out fuses of other types of fuse link' holding devices embodying refillable features will ensue.

The improved indicator is adapted for use with any form of fuse strip that is arapplication thereof.

ranged for disconnection by burning out, and may be applied in any vpracticable position on the cartridge, or to any fuse-holding device other than the cartridge hereinbefore explained and to demonstrate one Moreover, the, improved indicator is indefinitely reusable with a number of fuse links or strips, or does not cease to be operative with the burning or blowing out 0f the one fuse link or stripito which it has been operatively applied. y The improved device may also be applied at any point along the length ofthe fuse link or strip with the same efficiency in service.

I claim as my invention:

l. A. blown fuse indicator consisting of a cylindrical casing removably insertible in the intermediate portion of a fuse cartridge, a spring actuated plunger mounted in and movable through opposite ends of the casing and provided with an enlarged indicating'means on its outer end and an intermediate disk movable Within the casing, and means within the casing engaging the intermediate disk for displacing the plunger from a set position.

2. An attachment for indicating the presence of a blown fuse consisting of a spring actuated plunger having an enlarged disk indicating means on its outer end and an 1ntermediate movement guiding disk, the inner end of the plunger being adapted to engage a fuse device.

3. A blown fuse indicating means consisting of a casing, a plunger mounted in the casing and having an enlarged disk indicating means on the outer end thereof and the inner end free to engage a fuse device, the inner end of the plunger and the casing having coperating means to hold the plunger outwardly in temporarily removable abnormal position during positioning of the fuse for engagement by the plunger, said plunger when normally in position in engagement with the fuse device being automatically movable to change the set position of the external indicating means to show when a fuse has been blown.

4. The combination with a refillable fuse device having a fuse therein, of a casing removably inserted in the intermediate portion of the said device and provided with a spring actuated plunger movable through opposite ends of the casing, the plunger having an enlarged indicating means on the outer end and the inner end adapted to enprovided with a spring-actuated plungerl having an indicating means on its outer end and the inner end free to engage a fuse, the inner end of the plunger being screwthreaded to engage a portion of the casing to hold the inner end of the plunger in cleared position relatively to the fuse gpplied to the device to replace a blown use.

6. The combination with a fuse link holding cartridge, of a casing removably mounted in the intermediate portion of the cartridge and having a plunger movable through opposite ends thereof, the plunger being provided with an 'enlarged flat indicating means on its outer exterior end, the opposite inner end of the plunger being free to engage a fuse link, a plunger disk on the intermediate portion of the plunger movable within the casing, and a spring surrounding the plunger between the said disk and the outer end of the casing to automatically force the plunger inwardly when the fuse link has blown, the indicating means at the outer end of the plunger being held at a distance from the outer end of the casing when the plunger is set in contact with a fuse link, the inner ends of the plunger and casing having coperating means to hold the plunger outwardly in abnormal position when applying a new link in the cartridge.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

WILLIAM H. HOLDORF. Witnesses:

'IHos R. CoLLINs, VIOLA HoLDoRF. 

